Transformation of Merkel cell carcinoma to ganglioneuroblastoma in intracranial metastasis

Pathologic Progression, Possible Origin, and Management of Multiple Primary Intracranial Neuroendocrine Carcinomas

BACKGROUND

Primary intracranial neuroendocrine carcinomas (NECs) are extremely rare malignant tumors with no previous reports of multiple ones in the literatures.

CASE DESCRIPTION

The clinical presentation, preoperative and reexamined magnetic resonance imaging findings, as well as histopathologic studies of a 56-year-old female subject with multiple intracranial NECs mimicking multiple intracranial meningiomas, who underwent 3 operations with left parietal craniotomy, right occipital parietal craniotomy, and left frontal craniotomy, separately and chronologically, are presented in this article. Noteworthy, the first and second tumors were confirmed as NECs exhibiting histologic characteristics of typical anaplastic meningiomas with features of whorl formation, while the third tumor was a typical NEC with features of organoid cancer nests. In other words, the first 2 lesions were diagnosed as meningioma as opposed to NEC. It was only after the third surgery that the pathology for the first 2 cases was reviewed and had a revised diagnosis. After the third surgical resection, the patient further received whole brain radiotherapy and systemic chemotherapy (temozolomide combined with YH-16). At her 10-month follow-up, the patient achieved a good outcome.

CONCLUSIONS

Multiple primary intracranial NECs are extremely rare. The tumor might be of arachnoidal or leptomeningeal origin, with histologic patterns that might lead to transformation and/or progression. Maximal surgical resection is warranted for symptomatic mass effect. Postoperative adjuvant treatments including radiotherapy and chemotherapy should be a recommended therapeutic modality.

Development of an Atypical Teratoid Rhabdoid Tumor in a Meningioma

We describe an atypical teratoid rhabdoid tumor (AT/RT) with a component of low-grade and anaplastic rhabdoid meningioma in a 7-year-old child. The AT/RT was uniformly negative for INI1 and displayed immunoreactivity for vimentin, P53, CD99, cytokeratins with AE1/AE3 antibodies, epithelial membrane antigen, β-catenin, smooth muscle actin, E-cadherin, and S-100 protein. AT/RT was continuous, with small foci of recognizable low-grade and anaplastic meningioma. The low-grade meningioma was INI1 positive with scattered INI1-negative nuclei, whereas the remaining tumor components were INI1 negative. A recurrent tumor 6 months after partial resection contained only INI1-negative AT/RT. This case supports the hypothesis that rare examples of AT/RT may emerge from a preexisting “parent” neoplasm as a result of a second hit mutation.

Progression of atypical extraventricular neurocytoma to anaplastic ganglioglioma

We report a childhood case of thalamic atypical extraventricular neurocytoma that progressed to highly anaplastic ganglioglioma after 8 years of dormancy after subtotal resection and chemotherapy. The neurocytoma displayed immunoreactivity only for synaptophysin, β-catenin, S100, and CD56. The ganglioglioma acquired strong immunoreactivity for chromogranin, glial fibrillary acidic protein, neuron-specific enolase, and p53 and showed a very high proliferation rate approaching 50% in some areas. Tumor transformation was associated with overexpression of components of the sonic hedgehog and Wnt developmental signaling pathways, which are known to regulate tumor-initiating cells in malignant brain neoplasms.